Biomedical subjects
Publications and source records attributed to Abass Alavi.
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INTRODUCTION: Our objective was to develop a technique for quantifying the extent of atherosclerosis in the aorta by combining standard uptake values (SUVs) in the aortic wall with volumetric data provided by computed tomography (CT). METHODS: Eighteen patients who had both 18-fluorodeoxyglucose (FDG)-positron emission tomography (PET) and contrast-enhanced CT of the chest and abdomen were selected. All had homogeneous diffuse FDG wall uptake in four segments of the aorta. We divided the patients into three groups according to their age and measured FDG uptake in all four segments of the aorta by calculating the mean SUV for each segment. On each axial CT image, region-of-interest tracings along the inner and outer wall contours of the aorta were generated. The inner surface area was subtracted from the outer surface area. The net area values for each segment were subsequently multiplied by slice thickness to calculate arterial wall volume. By multiplying SUV with wall volume, we were able to calculate the atherosclerotic burden (AB) for each segment of the aorta. We compared the aortic wall volumes, SUVs and AB values in each arterial segment for each age group. RESULTS: In each aortic wall segment, AB values, SUVs and wall volumes increased with age (P<.05). CONCLUSION: AB can be used as an indicator of the extent of the atherosclerotic process in the aorta through the use of both metabolic and morphologic data provided by FDG-PET and CT, respectively. This may allow for the optimal screening, diagnosis and management of patients with this common and potentially lethal disorder.
We report a patient with anti-Yo associated paraneoplastic cerebellar degeneration (PCD) whose tumor was demonstrated 5 years after developing PCD and had strong expression of Yo (cdr2) antigen. Review of this case along with clinical series and studies of tumor growth rates question the effectiveness of the anti-tumor immune response. These studies and similar cases suggest that the tumor may trigger the anti-Yo immune response at microscopic stages of development. An overwhelming majority of anti-Yo positive patients eventually develop a detectable malignancy, which argues in favor of a poorly effective or non-sustained anti-tumor immune response.
We assessed the presence and the degree of alteration of the regional blood flow (rCBF) as visualized by Tc-99m HMPAO brain rest SPECT in the sensory motor cortex and subcortical structure in spinal cord injury (SCI) patients, who suffered from various levels of motor and sensory function loss. Twenty-two patients (mean age: 42.1+/-13.4 years, 18 M, 4 F) and 11 control subjects (mean age: 32.2+/-6.4 years, 8 M, 3 F) participated in this study. The spinal cord injury group was consisted of 2 groups (14 paraplegic and 8 tetraplegic patients). The corticocortical rCBF ratios were calculated by using region of interests obtained from 34 cortical areas on coronal slices. Significantly reduced rCBF were measured from 11 cortical areas in tetraplegic patients and 11 cortical areas in paraplegic patients. Some of these areas were different in each group. In the tetraplegic group, significant reduction was observed in the following rCBF areas: left anterior cingulate gyrus, left medial supplementary motor area, bilateral front and back aspects of posterior cingulate gyrus, right lateral primary motor area, right medial primary sensory area, bilateral putamen, and right cerebellum. In the paraplegic group, reduced rCBF areas were as follows: bilateral anterior cingulate gyrus, right lateral supplementary motor area, left front aspect of posterior cingulate gyrus, left lateral primary motor area, bilateral back aspects of posterior cingulate gyrus, right medial primary sensory area, left lateral primary sensory area and bilateral putamen. In conclusion, in some of the movement-cortical and subcortical areas having significantly reduced blood flow in SCI may be helpful to demonstrate the disrupted areas of rCBF by SPECT. We believe that it may be useful if these findings should be considered during the evaluations related to the reorganization in SCI cases.
BACKGROUND: We hypothesized that F-18 FDG-PET could be a useful, functional imaging modality for assessing the initial staging, response to therapy and follow-up of children diagnosed with lymphoma. OBJECTIVE: To assess the role of whole-body F-18 FDG-PET imaging in patients with lymphoma as an initial staging modality and to measure its predictive value for monitoring the response to therapy and disease recurrence compared to CT and clinical follow-up studies. MATERIALS AND METHODS: As part of their routine clinical care, 24 patients with histologically proven lymphoma (18 Hodgkin disease and 6 non-Hodgkin lymphoma) underwent an F-18 FDG-PET and a CT scan. A total of 28 studies were performed and the entire set of scans retrospectively reviewed. Seven studies were performed for initial staging, 12 for monitoring therapy response and 9 for detecting recurrence. Initial diagnosis was confirmed by histopathology while the gold standard at follow-up was established by clinical follow-up, additional imaging modalities and/or biopsy. F-18 FDG-PET was visually compared to CT on a lesion-by-lesion basis. Fifteen anatomic regions (seven nodal and eight extranodal) were analyzed. RESULTS: Of the 414 regions analyzed, PET and CT were concordant in 366 (positive in 16 and negative in 350). Discordance was found in 48 regions. Overall sensitivities, specificities, and positive and negative predictive values were 78%, 98%, 94% and 90% for F-18 FDG-PET and 79%, 88%, 90% and 46% for CT, respectively. CONCLUSION: F-18 FDG-PET imaging is a useful technique for the staging and follow-up of pediatric patients with lymphoma.
UNLABELLED: The present study was aimed to determine the clinicopathologic factors that predict false negative (FN) PET results in these patients. METHODS: A total of 116 breast lesions in 111 patients (pre-menopausal 45; perimenopausal 15; post-menopausal 51) with known or suspicious of breast cancer who underwent FDG-PET scans for staging, were included in this study. The median age was 52+/-11 years (range 32-79 years). All PET studies results were correlated with follow-up surgical pathology results. A cut off value of 2.5 was considered for positive or negative PET results. Univariate and multivariate analyses were performed to identify factors associated with FN results. RESULTS: Of 116 breast lesions, 85 were malignant and 31 were benign on histopathology. Of the 85 malignant lesions, 41 were true positive (TP) and 44 were FN. Among the 31 benign lesions, 30 were true negative and one was false positive. There was significant difference in the tumor size (p=0.003) and tumor grade (p=0.001) in patients with TP and FN PET results. Multivariate logistic regression demonstrated that tumor size (< or =10 mm) and low tumor grade were independently associated with FN results. No significant relationship of FN PET results was found with age, menopausal status, tumor type, c-erbB-2, estrogen and progesterone receptors, sentinel lymph node or distant metastasis, parenchymal density and multifocality of primary breast tumor. CONCLUSION: In present study, tumor size and tumor grade are independent factors that predict FDG-PET results. Smaller tumors (< or =10 mm) and low-grade tumors are strong predictor of FN FDG-PET results.
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We aimed to compare the accuracy of fluorodeoxyglucose positron emission tomography (FDG-PET) with technetium-99m sulfur colloid (111)indium-labeled white blood cell scintigraphy (TcSC-Ind BM/WBC) in diagnosis of periprosthetic infection. Eighty-nine patients with 92 painful hip prostheses were recruited prospectively and given the option of undergoing either combined FDG-PET and TcSC-Ind BM/WBC or FDG-PET only. FDG-PET correctly diagnosed 20 of the 21 infected cases (sensitivity, 95.2%) and ruled out infection in 66 of the 71 aseptic hips (specificity, 93%) corresponding to a positive predictive value of 80% (20/25) and a negative predictive value of 98.5% (66/67). TcSC-Ind BM/WBC correctly identified 5 of the 10 infected cases (sensitivity, 50%) and 39 of 41 aseptic cases (specificity, 95.1%) corresponding to a positive and negative predictive values of 41.7% (5/12 cases) and 88.6% (39/44 cases), respectively. Based on these preliminary results, FDG-PET appears to be a promising diagnostic tool for distinguishing septic from aseptic painful hip prostheses.
AIM: To determine whether or not fluorodeoxyglucose positron emission tomography (FDG PET) imaging when positive could obviate the necessity for sentinel lymph node biopsy and for complete axillary node dissection in patients with breast cancer. METHODS: A total of 80 female patients with a histological diagnosis of breast cancer and clinically negative axillary nodes underwent an FDG PET and sentinel lymph node biopsy (SLNB) or total axillary dissection for staging of axilla. Both SLNB and axillary dissection were performed in 72 patients, while eight patients had total axillary dissection without SLN biopsy. RESULTS: Of the 80 patients, 36 had lymph node metastasis on histopathology. SLNB was positive for metastasis in 35 (97%) of 36 patients (29 macrometastasis and seven micrometastasis). In the patient with false negative SLNB, the lymph node was completely replaced by the tumour. The FDG PET was true positive in 16 of 36 patients (sensitivity, 44%). There were two false positive studies with FDG PET, resulting in a specificity of 95%. The positive predictive value and accuracy of FDG PET for the detection of axillary lymph node metastasis were 89% and 72%, respectively. Univariate analysis revealed that higher grade of tumour, increased size and number of axillary lymph nodes were significantly associated with positive FDG PET results for axillary staging. CONCLUSION: FDG PET cannot replace histological staging using SLNB in patients with breast cancer. However, FDG PET has a high specificity and positive predictive value for staging of the axilla in these patients. The patients with higher grade of tumour, larger size and higher number of axillary lymph nodes may be considered for FDG PET scan for axillary staging.
OBJECTIVES: To assess the usefulness of [18F]fluorodeoxyglucose positron emission tomography in the detection of bone marrow involvement in malignant lymphoma, and its impact in clinical management. METHODS: One hundred and six consecutive patients with a confirmed diagnosis of lymphoma, referred for staging or restaging of Hodgkin's lymphoma (n=18) or non-Hodgkin's lymphoma (n=88), were reviewed retrospectively. A positron emission tomography scan and bone marrow biopsy of the iliac crest were performed in all patients. The assessment of bone marrow involvement by lymphoma was confirmed by histology and/or progression of bone marrow lesions in clinical follow-up. RESULTS: In 28 of 106 patients, bone marrow involvement was found. Positron emission tomography was more sensitive (86%) than bone marrow biopsy (57%). Positron emission tomography and bone marrow biopsy were concordant by positive correlation in 12 of 28 cases (43%) and by negative correlation in 77 of 78 cases (99%). Ten cases of non-Hodgkin's lymphoma and two cases of Hodgkin's lymphoma with positive positron emission tomography results and an initial negative bone marrow biopsy showed clinical progression of the bone marrow lesions and/or subsequent positive histology. These were considered as false-negative results for bone marrow biopsy. In seven of the 12 positive cases with negative bone marrow biopsy, positron emission tomography uptake distant from the site of the biopsy was seen. In four cases of follicular lymphoma, the bone marrow biopsy was positive and the positron emission tomography scan was normal. CONCLUSIONS: Positron emission tomography and bone marrow biopsy are complementary in assessing the presence of bone marrow involvement in patients with malignant lymphoma. In our series, positron emission tomography was more sensitive than bone marrow biopsy in Hodgkin's and non-Hodgkin's lymphoma, except in follicular lymphoma.
Gastric FDG uptake is a common observation on positron emission tomography (PET), which is most frequently caused by a nonmalignant etiology. However, a malignant lesion in the region of the stomach must not be overlooked. A 48-year-old woman with a history of melanoma in the esophagus and status postesophagectomy underwent FDG PET to evaluate for tumor recurrence. The images demonstrated hypermetabolism in the region of the location of the stomach. However, considering that the patient had a history of a stomach pullthrough procedure, we felt that this activity was nongastric and represented tumor recurrence, which was subsequently confirmed by computed tomography scan and histopathologic examination.
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PURPOSE: In an effort to optimize sentinel lymph node (SLN) mapping for breast cancer, sites of mapping agent administration and types of mapping agents used continue to be evaluated. This study compares SLN mapping using peritumoral (PT) or subareolar (SA) injection of radiolabeled colloid and examines the relative contributions of radiotracer and blue dye to SLN identification. MATERIALS AND METHODS: A retrospective review was performed of 456 patients with breast cancer and clinically negative axillae who underwent SLN mapping. Sequential groups of patients were injected with filtered Tc-99m SC, 326 peritumorally (group 1) and 130 subareolarly (group 2). All patients had intraoperative SA injection of 1% isosulfan blue dye. RESULTS: The SLN identification and isotope success rates were 97% and 96% in group 1 and 98% and 98% in group 2, respectively. Eighty-one patients (25%) in group 1 and 44 patients (34%) in group 2 had positive SLNs. Of these patients, 15% from group 1 and 14% from group 2 had only positive nodes detected by radiotracer, and 9 of these patients (6 from group 1 and 3 from group 2) had other nodes identified by both radiotracer and blue dye that were negative for metastases. Six percent of patients with positive SLNs were upstaged because of use of radiotracer. CONCLUSIONS: PT and SA injection of radiotracer have comparable success rates for axillary SLN identification. Given that 15% of patients in group 1 and 14% in group 2 had only positive SLNs detected by radiotracer, independent of site of administration, radiotracer remains essential for optimizing breast SLN mapping.